Create ER diagram

[spannercode]

As a developer I would like to see the ER diagram of the entities involved in the mail service MVP.

[saisab29]

Initial ER Diagram

[saisab29]

@spannercode dai

[spannercode]

A few comments:

• Looks good
• Changes requested:
  -- For all entities, lets add a consistent created_at and updated_at timestamps
  -- name field for each entities, we can just keep it as name instead of prepending the entity name in the front. Eg. namespace_name --> name inside namespace entity.
  -- Lets extract out the sender details from campaign into a separate entity called campaign_senders. This refers to the server id, and adds other fields like from, email
  -- On campaigns entity, send_at might not be a fit because on a single campaign there could be hundreds of emails that are sent and not just one so this field here could be misleading in the meaning it could represent.

[saisab29]

Changes made:

• Added created_at, updated_at timestamps to all the entities.
• Updated name field for all entities
• Added new entity campaign_senders to store sender details. It references to server id.
• Removed send_at from campaigns entity
• Added junction table (list_contacts) for resolving many-to-many relationship between lists and contacts

[spannercode]

Currently the user management is not considered for the MVP. The only user is the authenticated admin who can perform all operations on the email service.